33willys

iTrader: (1)

Thinking about changing my thermostat from 180 to 160. Engine is stock LM4 in my '39 Chevy. Will a thermostat change mess with my tune?

Michael Yount

iTrader: (1)

Why are you changing it?

33willys

iTrader: (1)

I live in southern NM and the temps go past 100 on a daily basis. I figure the extra 20 degrees of "padding" will help while running the A/C when I need it most.

Michael Yount

iTrader: (1)

If the system has trouble rejecting enough heat to stay at 180F, it can't reject the additional heat needed to get down to 160F. If it's struggling - you need more air, and/or bigger/better heat exchangers. Lower T'stat won't help.

LS6427

iTrader: (2)

A 160*F t-stat will make things worse.....even with fans that run all the time.

You must have the t-stat close and allow enough "sit" time for the coolant in the radiator to cool off before it goes back into the engine.

I had a 160*F tstat in my engine....hot *** South Florida. It ran hot all the time after my brand new 436ci stroker went in. A few weeks dealing with that crap I put in a 180*F. problem solved. Ran nice and cool after that. I did not touch the tune the dyno tuner did to run with the 160*F tstat....it all worked out fine for the next 12 years.

What will happen with a 160*F tstat is it will reach a point where the coolant cannot cool down and the tstat will never fully close....the coolant will keep circulating and just get hotter and hotter.....Then your doomed and it will overheat. Coolant must have sufficient "sit" time in the radiator before entering back into the engine block/heads.

.

Michael Yount

iTrader: (1)

Well....old wives tale....it doesn't work that way. With increased heat load you WANT more coolant flow thru rad. That's why the water pump SPEEDS UP with revs. If you've ever had a t'stat stick open in cool weather, it'll over cool like crazy. The greater the flow of air over the rad and coolant through the rad -- the greater the heat transfer. That's how it works.

Project GatTagO

iTrader: (7)

Stock thermostat is 187 and I see no reason to change that. My Cougar runs between 193 and 200, no matter what the ambient temperature is.

Andrew

Michael Yount

iTrader: (1)

As does mine Andrew -- with the 187F t'stat on the inlet side, if the fan and rad have the capacity to reject enough heat and fan activation control temps don't exceed 200F - then head temps will be right there in the 193F-200F range.

jimmyg

I have a 160 . Car runs 175 -180. hottest I've seen it was 190 on a 100 degree day sitting in traffic with Ac on. But, I have derale 4000cfm duel fans run by a painless pwm set up.

gagliano7

Same deal with my 160 stat. On the highway 174-176 sitting in traffic 180-186 i have a single 3500 fan.

gagliano7

I think you had air in the system with the 160 stat or there was something wrong with the stat. I have had 160 stats in 7 different ls motors and they all ran at 174-178 on the highway and what ever the fans were set at for sitting in traffic or idle around 185-190.

oldstv

I have to change the o-ring in my housing "or at least look at it because of a leak" would you guys suggest keeping the stock stat "480hp crate from Summitt" or going to a 160? My gauges are Dakota Digital and I have been told they typically show warm.

kingtal0n

iTrader: (1)

I would also prefer the 160*F Due to local climate being always hot, and other factors. 160 isn't that far off from 180*, and although 180*F is good for many applications, it really does help to have the cooling "padding" like the op was saying, the ability to get the engine below 180*F when you want to by using a fan is priceless sometimes.

I fully support and will also be following this notion. I will still run the engine 180-190*F when cruising for economy, but on the extra hot days etc... I will try to keep it a bit lower than 180 if doing any hard driving. For example.